A Quick tip.

Underwired bras are generally not machine washable. In the past I ignored this to my peril!
My washing machine wouldn't empty and I had to call a service engineer.
One of the wires had come lose and stuck in the machine.

To make them machine washable, place them inside a jeans leg or similar,
and use two elastic bands to secure either side.

Of course, make sure the other item is fairly strong and colourfast.